1. Field of the Invention
The present invention relates to cooling apparatuses for hybrid vehicles which are driven by an engine and a motor, and in particular, to a technique of performing a cooling operation based on heat resisting allowable temperatures assigned to various kinds of electric devices.
2. Description of the Related Art
In known cooling apparatuses, a plurality of cooling systems are each provided for a plurality of electric systems such as a motor, battery, inverters, and the like, which are built into a hybrid vehicle, and the cooling systems are arranged and connected in parallel. Japanese Unexamined Patent Application, First Publication No. Hei 11-107748 discloses an example of such an apparatus.
Additionally, in such a conventional cooling apparatus, the diameter of a pipe, through which a refrigerant flows, can be changed according to the heating value of each cooling system, and flow control valves for controlling the flow rate of each cooling system are provided. Therefore, a larger quantity of refrigerant flows through a cooling system which has a larger heating value.
However, since the plurality of electric devices are arranged in parallel, the piping arrangement for circulating the refrigerant is complicated.
Additionally, the operation of controlling a plurality of flow control valves is complicated. Furthermore, the flow rate of the refrigerant is changed by controlling the degree of opening of each flow control valve. Therefore, the circulating pump for circulating the refrigerant in the cooling circuit is always working, so that the power consumption of the battery system for supplying electric power to the circulating pump is unnecessarily increased.
In consideration of the above circumstances, an object of the present invention is to provide a cooling apparatus which has a simple structure and which can efficiently cool a plurality of electric devices.
Therefore, the present invention provides a cooling apparatus built into a hybrid vehicle, comprising:
a cooling circuit (e.g., cooling circuit 10a in an embodiment explained below) including a plurality of serially-connected cooling systems (e.g., battery cooling system 14, PDU cooling system 15, D/V cooling system 16, first motor cooling system 17, and second motor cooling system 18 in the embodiment explained below) for cooling a plurality of electric devices by circulating a refrigerant, wherein the electric devices include at least a motor (e.g., first motor in the embodiment explained below) for driving the vehicle, a battery system, and an inverter (e.g., power drive unit PDU in the embodiment explained below) for supplying electric power to the motor;
a circulating pump (e.g., refrigerant circulating pump 13 in the embodiment explained below) for circulating the refrigerant through the cooling circuit; and
a radiator (e.g., electric device radiator 11 in the embodiment explained below) which is serially connected to the cooling systems in the cooling circuit and has a refrigerant outlet (e.g., refrigerant outlet 11a in the embodiment explained below) from which a refrigerant is supplied, wherein:
the serially-connected cooling systems are arranged in a manner such that heat resisting allowable temperatures, assigned to the electric devices which respectively correspond to the cooling systems, increase from the cooling system closest to the refrigerant outlet to the cooling system farthest from the refrigerant outlet in the cooling circuit, wherein each heat resisting allowable temperature is the maximum temperature at which the relevant electric device can operate.
According to the above structure, the plurality of the cooling systems for circulating and supplying the refrigerant to the electric devices which are built into the vehicle are serially connected via the radiator, so that the cooling circuit is formed. Therefore, the piping arrangement for circulating the refrigerant can be simplified.
In addition, the serially-connected cooling systems are arranged along a refrigerant circulating path in a manner such that the heat resisting allowable temperatures assigned to the electric devices increase in the order of arrangement of the electric devices. That is, the electric devices having higher priority are located at the upstream side of the cooling circuit so as to reliably cool these electric devices, while the electric devices having relatively lower priority are located at the downstream side of the cooling circuit. Therefore, the plurality of the electric devices can be efficiently cooled, thereby improving the fuel consumption of the vehicle.
The cooling apparatus may further comprise:
an air-conditioner condenser (e.g., air-conditioner condenser 21 in the embodiment explained below) which is provided for an air conditioner of the vehicle and which faces the radiator; and
a cooling fan (e.g., condenser cooling fan 19 in the embodiment explained below) which faces the air-conditioner condenser, wherein:
the radiator and the air-conditioner condenser are cooled by the cooling fan.
According to this structure, the air-conditioner condenser is located in a manner such that the air-conditioner condenser faces the radiator which is connected to the cooling circuit for cooling the electric devices (which include at least the motor, the battery system, and the inverter). The radiator and the air-conditioner condenser are cooled by the cooling fan which faces the air-conditioner condenser. Therefore, the radiator and the air-conditioner condenser can be efficiently cooled by the common cooling fan, thereby simplifying the structure of the apparatus.
The present invention also provides a cooling apparatus built into a hybrid vehicle, comprising:
an engine radiator (e.g., engine radiator 12 in the embodiment explained below) connected to an engine cooling system (e.g., engine cooling system 12a in the embodiment explained below) which cools an engine by circulating a refrigerant, wherein the engine outputs a driving force of the vehicle;
a radiator cooling fan (e.g., radiator cooling fan 20 in the embodiment explained below) which faces the engine radiator;
a cooling circuit (e.g., cooling circuit 10a in the embodiment explained below) including a plurality of serially-connected cooling systems (e.g., battery cooling system 14, PDU cooling system 15, D/V cooling system 16, first motor cooling system 17, and second motor cooling system 18 in the embodiment explained below) for cooling a plurality of electric devices by circulating a refrigerant, wherein the electric devices include at least a motor (e.g., first motor M1 and second motor M2 in the embodiment explained below) for outputting driving force according to a driving state of the vehicle, a battery system, and an inverter (e.g., power drive unit PDU in the embodiment explained below) for supplying electric power to the motor;
a circulating pump (e.g., refrigerant circulating pump 13 in the embodiment explained below) for circulating the refrigerant through the cooling circuit; and
an electric device radiator (e.g., electric device radiator 11 in the embodiment explained below) which is serially connected to the cooling systems in the cooling circuit and has a refrigerant outlet (e.g., refrigerant outlet 11a in the embodiment explained below) from which a refrigerant is supplied, wherein:
the serially-connected cooling systems are arranged in a manner such that heat resisting allowable temperatures, assigned to the electric devices which respectively correspond to the cooling systems, increase from the cooling system closest to the refrigerant outlet to the cooling system farthest from the refrigerant outlet in the cooling circuit, wherein each heat resisting allowable temperature is the maximum temperature at which the relevant electric device can operate.
The above structure comprises the electric device radiator which is connected to the cooling circuit for cooling the electric devices which include at least the motor, the battery system, and the inverter. This electric device radiator is independent of the system including the engine radiator. The cooling systems for circulating and supplying the refrigerant to the electric devices are serially connected via the electric device radiator, thereby simplifying the piping arrangement for circulating the refrigerant.
In addition, the serially-connected cooling systems are arranged along a refrigerant circulating path in a manner such that the heat resisting allowable temperatures assigned to the electric devices increase in the order of arrangement of the electric devices. That is, the electric devices having higher priority are located at the upstream side of the cooling circuit, while the electric devices having relatively lower priority are located at the downstream side of the cooling circuit. Therefore, the plurality of the electric devices can be efficiently cooled, thereby improving the fuel consumption of the vehicle.
Preferably, the electric device radiator faces the engine radiator. In this case, the electric device radiator, which is independent of the system including the engine radiator, can also be cooled by the radiator cooling fan which faces the engine radiator. Therefore, it is unnecessary to provide a dedicated cooling fan for the electric devices, thereby simplifying the structure of the apparatus and performing an efficient cooling operation.
The cooling apparatus may further comprise:
an air-conditioner condenser (e.g., air-conditioner condenser 21 in the embodiment explained below) which is provided for an air conditioner of the vehicle and which faces the engine radiator; and
a condenser cooling fan (e.g., condenser cooling fan 19 in the embodiment explained below) which faces the air-conditioner condenser, wherein:
the electric device radiator faces the air-conditioner condenser.
According to this structure, the engine radiator and the electric device radiator can be efficiently cooled by the condenser cooling fan for cooling the air-conditioner condenser and the structure of the apparatus can be simplified.
Each cooling apparatus as explained above may further comprise:
a plurality of temperature sensors (e.g., refrigerant temperature sensor 22, battery temperature sensor 23, first temperature sensor 24, second temperature sensor 25, and first motor temperature sensor 26 in the embodiment explained below) for detecting temperatures of the electric devices, wherein:
a duty factor of the circulating pump, which is the rate of energizing the circulating pump, is changed according to detection signals output from the temperature sensors.
According to this structure, based on the detection signals output from the temperature sensors, values indicating the cooling performance required by the plurality of electric devices can be calculated, and the operation of the circulating pump for refrigerant (i.e., the speed of rotation of the pump) is controlled based on these required values. Therefore, in comparison with a control operation in which the circulating pump is always driven under fixed conditions, the circulating pump can be more efficiently driven and controlled. Accordingly, the power consumption of the circulating pump can be reduced and the fuel consumption of the vehicle can be improved.
The duty factor may be calculated for each detection signal output from each temperature sensor, so as to obtain a plurality of duty factors, and the circulating pump is driven based on the maximum value among these duty factors. In this case, the circulating pump is driven based on the maximum value among the values indicating the cooling performance (i.e., duty factors) required by the plurality of electric devices. Therefore, the electric devices can be reliably cooled and excessive cooling or the like can be prevented, thereby improving the fuel consumption of the vehicle.
The cooling apparatus may further comprise:
a refrigerant temperature sensor (e.g., refrigerant temperature sensor 22 in the embodiment explained below) for detecting the temperature of the refrigerant in the vicinity of the refrigerant outlet of the electric device radiator, wherein:
the radiator cooling fan is driven when the temperature of the refrigerant detected by the refrigerant temperature sensor is larger than a predetermined temperature.
According to this structure, in addition to the case in which the engine water temperature or the like is relatively high and a request for cooling the engine radiator is output in the control operation, even when such a request for cooling the engine radiator is not output, if the temperature of the refrigerant for the electric devices is larger than a predetermined temperature, then the radiator cooling fan is driven, thereby cooling the electric device radiator. Therefore, the electric device radiator can be reliably cooled.
The cooling apparatus may further comprise:
a refrigerant temperature sensor (e.g., refrigerant temperature sensor 22 in the embodiment explained below) for detecting the temperature of the refrigerant in the vicinity of the refrigerant outlet of the electric device radiator, wherein:
the condenser cooling fan is driven when the temperature of the refrigerant detected by the refrigerant temperature sensor is larger than a predetermined temperature.
According to this structure, in addition to the case in which the temperature of the air-conditioner condenser is relatively high and a request for cooling the air-conditioner condenser is output in the control operation, even when such a request for cooling the air-conditioner condenser is not output, if the temperature of the refrigerant for the electric devices is larger than a predetermined temperature, then the condenser cooling fan is driven, thereby cooling the electric device radiator. Therefore, the electric device radiator can be reliably cooled.
Typically, in the above cooling apparatuses:
the battery system, the inverter, and the motor are serially connected in this order, wherein the battery system is closest to the refrigerant outlet in the cooling circuit; and
the heat resisting allowable temperatures, which are respectively assigned to the battery system, the inverter, and the motor, increase in this order.
Accordingly, the refrigerant is supplied to the battery system, the inverter, and the motor in this order, where the corresponding heat resisting allowable temperatures increase also in this order. Therefore, the electric devices can be suitably cooled, thereby improving the fuel consumption of the vehicle.